Lesões histológicas no sistema nervoso central de cães com encefalite e diagnóstico molecular da infecção pelo vírus da cinomose canina / Histopathological lesions in the central nervous system of dogs with encephalitis and molecular diagnosis of canine distemper virus infection

RESUMO

Dez amostras de urina de cães que apresentavam sinais clínicos sistêmicos e neurológicos indicativos da infecção pelo vírus da cinomose canina (CDV) foram analisadas pela técnica da reação em cadeia pela polimerase precedida de transcrição reversa (RT-PCR) para a detecção do RNA do CDV. O exame histopatológico foi realizado em fragmentos de cérebro, cerebelo e bexiga. Como controle negativo foram colhidos fragmentos de órgãos e urina de quatro cães sem sinais clínicos de doença infecciosa e que morreram por outras causas. Todos os cães (9/10) positivos em RT-PCR apresentaram alterações histológicas no cérebro e cerebelo, características de encefalite aguda (5/9) ou crônica (4/9) compatíveis com as causadas pelo CDV. Um dos cães com alterações clínicas neurológicas semelhantes às observadas em cinomose foi negativo na RT-PCR e apresentou alterações histopatológicas inespecíficas. Nas amostras de bexiga não foram observadas lesões histológicas. Todas as amostras biológicas provenientes dos cães-controle foram negativas na RT-PCR (urina) e não apresentaram alterações histológicas (fragmentos de órgãos). O trabalho evidenciou a especificidade da RT-PCR no diagnóstico precoce e ante mortem na infecção pelo CDV. (AU)

ABSTRACT

The reverse transcription-polymerase chain reaction (RT-PCR) was used to detect canine distemper virus (CDV) RNA in 10 urine samples from dogs that had died with clinical systemic and neurological signs indicative of CDV infection. Brain, cerebellum and urinary bladder fragments were collected for histopathological examination. For the negative control, urine and organ fragments were collected at necropsy from four dogs without clinical symptoms of infectious diseases that had died from other causes. The dogs positives in RT-PCR (9/10) presented histological lesions in the brain and cerebellum characteristic of acute (5/9) or chronic (4/9) encephalitis compatible with those caused by CDV. One of the dogs with neurological signs similar to those observed in canine distemper was negative in RT-PCR and presented non-specific histopathological alterations that could be associated to others nervous system diseases. Although the RT-PCR detected the CDV in urine of nine dogs with clinical signs of distemper, no histopathological alterations were observed in any of the urinary bladder samples. All the biological samples from the control dogs were negative in RT-PCR and did not present any histopathological alterations in organ. Besides describing the most characteristic histopathological lesion found in the central nervous system of dogs with acute and chronic encephalitis due to canine distemper, this study also showed the specificity of the RT-PCR technique in early and ante mortem diagnosis of CDV infections.(AU)